Traditionally, many dairy operations rely heavily on corn as grain and silage for their ration. While corn can be an economical source of dry matter and energy, its value diminishes if high levels of mycotoxins are present.
Cows that consume feed contaminated with mycotoxins – which include natural toxins made by various species of molds – may suffer a host of various metabolic disruptions that lead to a loss of milk production, hormonal imbalance and reduced reproductive performance.
What’s the risk?
Though ruminants are less vulnerable to mycotoxin toxicity than non-ruminants because they are able to detoxify most of them, mycotoxins can still be problematic.
Mycotoxins fed to cattle can eat away at your hard-earned dollars by impacting feed intake, growth rates, milk production and even fertility.
The impact on your herd is not necessarily the same across the board, especially with seasonal variances and the variability in other potential challenges such as nutritional, disease, environmental and management.
In an article titled “A wet fall is cause for mycotoxin concerns,” retired professor and dairy nutrient extension specialist with the University of California – Davis Peter Robins writes:
“At-risk cattle include calves with limited rumen function; cows with suboptimal rumen bacterial populations, such as fresh cows with low intakes; cows with high ruminal passage rates, such as high-producing cows; and recently bred cows.”
Mycotoxins are actually formed as secondary metabolites by molds to reduce the activity of the molds or bacteria. They require both nutrients and water to grow. Since feedstuffs such as corn, wet hay and silage can provide both, contamination can occur easily and suddenly.
Likewise, in the habitual rhythm of daily feeding chores, it can be easy to overlook moldy ingredients. Their development largely depends on weather and growing conditions, as well as the harvest and storage of various feedstuffs.
The latest toxic trends
Recently, Dairyland Laboratories released a report summarizing mycotoxin contamination. They analyzed corn grain and silage samples collected by their customers in the Northeast and Midwest from Sept. 1, 2023, through June 24, 2024. The research found concerning levels of various mycotoxin varieties that are on the rise and of high importance for dairy producers in all regions.
The mycotoxins of primal concern for livestock producers are two common mycotoxins produced by fusarium molds: zearalenone and vomitoxin, aka deoxynivalenol (DON).
Due to its chemical structure, zearalenone mimics estrogen. Once ingested and absorbed into the body, it causes significant repercussions on all aspects of fertility in most livestock species.
Zearalenone has also been shown to decrease immune responses, feed digestibility and can result in inefficient animal production and reproduction.
While DON mainly affects swine, it depresses feed intake and gain in cattle even at very low levels. DON has also been used as a marker to indicate the feedstuff may be contaminated with other mycotoxins.
One of the most notable details from the Dairyland Laboratories report is the levels of zearalenone in the submitted samples. Zearalenone was detected in 75% of the samples, with corn silage from the Northeast showing higher levels than that from the Midwest. Additionally, the level of zearalenone in corn grain has increased from the three-year average of 50%.
DON was found in 87% of the samples, with the Northeast again seeing slightly higher levels than the Midwest.
Other noteworthy mycotoxins identified included HT2 toxin, T-2 toxin and fumonisin. HT2 toxin, a type of TK toxin, was detected in slightly less than half of all samples analyzed. T-2 toxin was found in approximately 15% of the samples, and fumonisin was present in about half.
The nature of the beast
Rations are often contaminated with more than one mycotoxin. Of the corn samples submitted for mycotoxin analysis this year at Dairyland Laboratory, 49% contained three or more mycotoxins. Contamination can result from multiple mycotoxins in a single feed ingredient or from several different ingredients in the ration. The combined effect can be additive or even synergistic, leading to more severe negative impacts. This is particularly true in non-research settings, where challenges such as heat stress, overcrowding and disease pressure from viruses and bacteria are common.
“Visible mold on silages indicates that mycotoxins may be present. If you see molds, inform your nutritionist, who can take a sample of the suspect silage and have it analyzed,” Robins writes. “Transport samples to the laboratory quickly since mycotoxins can be produced in the presence of oxygen after sampling. While most mycotoxins listed above can be analyzed for, the assay costs may be high, although not as high as the costs of animal losses if toxicosis occurs.”
Regardless of level or mycotoxin type present, eradicating it from your feed program is essential for achieving optimal nutrition.
Dairies should remain on guard
Proper management is the key to avoid mold growth, and that begins at harvest. Many mycotoxins are produced even before the ensiling process begins, but there are a fair amount of issues that can happen during storage. Recently, Dr. John Goeser has authored thoughts about excessive rainfall in much of the Corn Belt and how that has potential to impact microbial development during the remainder of the growing season.
Harvesting and storing at the proper moisture and pH levels are a large part of the puzzle, but there are also a variety of inoculants and other additives to help in this process. Proper moisture, packing, chop length and using an inoculant containing Lactobacillus buchneri aid in the reduction of mold and spoilage yeasts.
Broad-spectrum biotoxin binders are effective in mitigating mycotoxin challenges and support a healthy intestinal environment, ultimately enhancing livestock performance and economic production.
Effective mycotoxin avoidance is crucial for maintaining the health and productivity of your dairy herd. Understanding the risks, staying vigilant and implementing proper feed management practices with appropriate additives significantly reduce the impact of mycotoxins on your operation.
